(a) Field of the Invention
The present disclosure relates to a transmission and reception method and an apparatus thereof, and more particularly, to a method for transmitting and receiving data using a variable guard interval, and a transmission apparatus and a reception apparatus.
(b) Description of the Related Art
When high speed data is transmitted in a single carrier using a multi-path channel, the transmission data is severely distorted due to inter-symbol interference (ISI). To solve this problem, orthogonal frequency division multiplexing (OFDM), a multi-carrier scheme in which high speed data is changed into low speed data and transmitted by using several sub-carriers, has been spotlighted. With the OFDM scheme, limited frequency resources may be effectively utilized, a high data transfer rate may be provided, and ISI generated by a multi-path channel may be removed by using a cyclic prefix (CP) as a guard interval.
Various communication standards such as digital video broadcasting (DVB), wireless local area network (WLAN), and the like, use a variable CP. Also, tens of pilot symbols are inserted into every OFDM symbol to allow for simple channel estimation and compensation, relative to a single carrier.
In a system using OFDM, a CP inserted to remove ISI generated by a multi-path channel lowers a data rate and causes loss of transmission power by a length thereof. Thus, in order to enhance a data rate in a system using a variable CP, a short CP is required to be used. However, if a CP length is short, ISI is generated by a multi-path channel, increasing a bit error rate, which rather lowers a data rate.
In addition, in order to estimate and compensate a multi-path channel, a transmission apparatus inserts tens of pilot symbols into every OFDM symbol and transmits the same, and a reception apparatus estimates a channel of a subcarrier to which a pilot symbol has been allocated, and in case of a subcarrier to which a pilot symbol is not allocated, the reception apparatus estimates a channel by using interpolation using the estimated channel value of the subcarrier. In general, a channel may be more accurately estimated when there are a large number of pilot symbols than when there are less. Thus, in order to enhance performance of the reception apparatus, it would be desirable to allocate more pilot symbols; however, in this case, a data rate is reduced.